Compared to single phase, 3 phase AC produces less ripple in the resulting DC waveform when rectified. At the capacitor filtering stage, it is much cleaner with less sag than filtered DC converted from single phase AC.
Are there any benefits to adding a pre-3 phase conversion of single phase AC before converting to DC? If the goal is to achieve the cleanest signal possible, does it perform better or worse than other methods? Finally, are there any power losses in doing so assuming the design uses an established efficient design using 3 single phase transformers connected a 3 phase transformer?